The long-term goal of this research is to determine the three dimensional structures of M-components. The source of the immunoglobulins and immunoglobulin fragments, whose crystal structures will be determined by x-ray diffraction, will be patients with monoclonal gammopathies. Most often these will be malignancies involving myelomatosis, Waldenstrom's macroglobulinemia, or cryoglobulinemia. M-components associated with benign monoclonal gammopathies will be studied whenever possible also in order to compare them with proteins from cancer patients. A continuous search, now in progress, will be maintained to find proteins that yield good quality single crystals. Since 1971, the search has turned up twenty-one M-components; attempts to grow single crystals of these proteins are now being made. One of them, Bence-Jones protein Rhe, which is half of a lambda type light chain, has been found to give a diffraction pattern of excellent quality chain, has been found to give a diffraction pattern of been determined to 3 A resolution. The plan is to solve it to the maximum resolution and to determine its primary structure as well. The proposed research could lead to a better understanding of cryoprecipitation phenomena, and it could provide information concerning pathogenesis of M-components. It will also add to our knowledge of the molecular structures and the mechanisms of action of antibodies.